Canine Dirofilaria immitis infection in a hyperenzootic area: examination by parasitologic findings at necropsy and by two serodiagnostic methods

A total of 174 dogs from an area hyperenzootic for Dirofilaria immitis were grouped into 4 age categories and necropsied; information was obtained on adult D immitis infections and on the presence of microfilariae. Serum samples from these dogs were examined by an enzyme-linked immunosorbent assay (ELISA) for antibody to adult D immitis and by an indirect fluorescent antibody test (IFAT) for antibody to microfilarial surface antigens. In dogs less than or equal to 5 months of age, necropsy demonstrated no evidence of infection; however, positive serologic results indicated that some of these dogs had prepatent infections. The percentage of dogs with ELISA titers (positive) increased with age, as did the percentage of dogs with adult D immitis infections. The IFAT results were positive in some dogs in each age category. Sera from all 29 dogs with occult infections were positive by ELISA. Sera from 6 of 20 dogs with occult dual-sex heartworm infections and 1 of 9 dogs with occult single-sex heartworm infections were positive by IFAT. For diagnosing occult dirofilariasis, the ELISA had a positive predictive value which increased with age of the dog to a maximum of 65.0% in dogs greater than or equal to 12 months of age; ELISA had a negative predictive value of 100% in all age groups. In contrast, positive and negative predictive values for the IFAT decreased with age of the dog to 60% and 37.5%, respectively, in dogs greater than or equal to 12 months of age.     

Time of zeranol implantation on growth, reproduction and calving of beef heifers

Zeranol implants were administered to 250 crossbred heifer calves at 1, 6 or 9 mo of age to evaluate growth, reproduction and calving performance. Heifers were assigned to eight treatment groups with 25 animals per group. Two additional groups of 25 heifers each were used to study the effects of multiple implants at two levels of nutrition on heifer performance. Implants at 1 mo of age (branding) increased heifer weights at 6 mo of age (weaning) by 5 kg (P = .08). Heifers receiving a combination of two implants gained faster (P less than .05) from weaning to breeding (6 to 13 mo) than controls or heifers implanted three times. Implants at either 6 or 9 mo increased (P less than .05) precalving pelvic areas (247 vs 241 cm2 and 248 vs 240 cm2 over controls, respectively). Implants did not affect the percent of heifers reaching puberty prior to breeding season. Conception rates in 62 d of breeding were comparable for implanted and control heifers (93 vs 96%), with the exception of heifers receiving implants at both 1 and 6 mo of age (56%). Calf birth weight, dystocia score, cow rebreeding rate and calf weaning weight were not affected by implant treatments. Heifers that received three implants and were fed at a high nutritional level (gained .62 vs .49 kg/d for regular level after weaning) tended (P greater than .10) to reach puberty at a higher rate prior to breeding and to have a higher total conception rate than implanted heifers on the regular nutrition level.     

An outbreak of malignant catarrhal fever in Père David's deer (Elaphurus davidianus)

Thirteen (54%) of 24 Père David's deer (Eluphurus duvidianus) imported from England died of malignant catarrhal fever (MCF) within a year of arrival at Invermay Agricultural Centre. The duration of clinical illness was from one to approximately 33 days, and the most common clinical signs were depression, a hunched stance and diarrhoea. On post-mortem examination, most deer showed recent localised haemorrhages, often into the large intestine. In all deer there was histological vasculitis especially in the brain.     

Bar suture (toggle pin) vs open surgical abomasopexy for treatment of left displaced abomasum in dairy cattle

Fifty-nine dairy cows with left displacement of the abomasum were randomly assigned to receive 1 of 2 treatments. Twenty-eight were treated by right paramedian abomasopexy via laparotomy, and 31 were treated by percutaneous fixation of the abomasum, using the bar suture or toggle pin technique. Comparisons of the 2 groups, at 4 follow-up examinations, yielded no significant differences in return to normal milk production, return to normal feed intake, mortality, culling rate, tissue reaction at the surgical site, or redisplacement up to 60 days into the subsequent lactation.     

When is a residue not a residue?

Residues of veterinary products in food animals have been the subject of much debate in recent years. This paper attempts to define and classify what is meant by the term 'residue' and to discuss the toxicological significance of various types of residues and how they may be controlled to ensure that no hazard results to consumers.     

Platelet‐Activating Factor and Evidence of Oxidative Stress in the Bronchoalveolar Fluid of Thoroughbred Colts during Race Training

Background: Inflammatory airway disease (IAD) is prevalent in young racehorses during training, being the 2nd most commonly diagnosed ailment interrupting training of 2‐year‐old Thoroughbred racehorses. Hypothesis: That stabling and exercise cause oxidative stress, release of platelet‐activating factor (PAF) and inflammation in airways of Thoroughbred colts. Animals: Colts in breeding farms (NC, n = 45), stabled for 30 days (EC, n = 40), and race trained (EX, n = 34). Methods: Cytological profile and parameters of bronchoalveolar lavage fluid (BALF) related to oxidative stress, bioactivity of the proinflammatory mediator PAF, catalase activity, and alveolar macrophage function. Results: Percentages of neutrophils and eosinophils in the BALF of the EX group were higher (5.4 ± 6.4% versus 0.9 ± 1.2%) than the upper limits for normal horses (3–5%). BALF from the EX group (45.6 ± 2.8 cells/μL of BALF) also displayed significantly (P= .017) higher total nucleated cell count. PAF bioactivity and the total protein concentration in the BALF were higher in the EX group (0.0683 ± 0.076 versus 0.0056 ± 0.007 340 : 380 nm ratio P= .0039, 0.36 ± 0.30 versus 0.14 ± 0.15 mg of proteins/mL of BALF P < .001). Concentration of BALF hydroperoxides was higher in the EC group (104.7 ± 80.0 versus 35.2 ± 28.0 nmol/mg of proteins, P= .013) and catalase activity was higher in the EX group (0.24 ± 0.16 versus 0.06 ± 0.02 μmol H₂O₂/min/mg of proteins, P= .0021). Alveolar macrophage phagocytosis (P= .048) as well as production of superoxide anion (P= .0014) and hydrogen peroxide (P= .0011) were significantly lower in EX group. Conclusions and Clinical Importance: Further studies should be performed to elucidate the role of PAF in the pathophysiology of IAD. Its presence in bronchoalveolar fluid of young athletic horses makes it a potential therapeutic target to be investigated.     

Measurement of C‐peptide concentrations and responses to somatostatin,glucose infusion,and insulin resistance in horses

Reasons for performing study: Hyperinsulinaemia is detected in horses with insulin resistance (IR) and has previously been attributed to increased pancreatic insulin secretion. Connecting peptide (C‐peptide) can be measured to assess pancreatic function because it is secreted in equimolar amounts with insulin and does not undergo hepatic clearance. Hypothesis: A human double antibody radioimmunoassay (RIA) detects C‐peptide in equine serum and concentrations would reflect responses to different stimuli and conditions. Methods: A validation procedure was performed to assess the RIA. Six mature mares were selected and somatostatin administered i.v. as a primed continuous rate infusion, followed by 50 nmol human C‐peptide i.v. Insulin and C‐peptide concentrations were measured in horses (n = 6) undergoing an insulin‐modified frequently sampled i.v. glucose tolerance test, and in horses with insulin resistance (n = 10) or normal insulin sensitivity (n = 20). Results: A human RIA was validated for use with equine sera. Endogenous C‐peptide secretion was suppressed by somatostatin and median (range) clearance rate was 0.83 (0.15–1.61) ml/min/kg bwt. Mean ± s.d. C‐peptide‐to‐insulin ratio significantly (P = 0.004) decreased during the glucose tolerance test from 3.60 ± 1.95 prior to infusion to 1.03 ± 0.18 during the first 20 min following dextrose administration. Median C‐peptide and insulin concentrations were 1.5‐ and 9.5‐fold higher, respectively in horses with IR, compared with healthy horses. Conclusions: Endogenous C‐peptide secretion decreases in response to somatostatin and increases after dextrose infusion. Results suggest that relative insulin clearance decreases as pancreatic secretion increases in response to dextrose infusion. Hyperinsulinaemia in insulin resistant horses may be associated with both increased insulin secretion and decreased insulin clearance. Potential relevance: Both C‐peptide and insulin concentrations should be measured to assess pancreatic secretion and insulin clearance in horses.     

Productivity,Respiration, and Light-Response Parameters of World Grassland and Agroecosystems Derived From Flux-Tower Measurements

Grasslands and agroecosystems occupy one-third of the terrestrial area, but their contribution to the global carbon cycle remains uncertain. We used a set of 316 site-years of CO₂ exchange measurements to quantify gross primary productivity, respiration, and light-response parameters of grasslands, shrublands/savanna, wetlands, and cropland ecosystems worldwide. We analyzed data from 72 global flux-tower sites partitioned into gross photosynthesis and ecosystem respiration with the use of the light-response method (Gilmanov, T. G., D. A. Johnson, and N. Z. Saliendra. 2003. Growing season CO₂ fluxes in a sagebrush-steppe ecosystem in Idaho: Bowen ratio/energy balance measurements and modeling. Basic and Applied Ecology 4:167–183) from the RANGEFLUX and WORLDGRASSAGRIFLUX data sets supplemented by 46 sites from the FLUXNET La Thuile data set partitioned with the use of the temperature-response method (Reichstein, M., E. Falge, D. Baldocchi, D. Papale, R. Valentini, M. Aubinet, P. Berbigier, C. Bernhofer, N. Buchmann, M. Falk, T. Gilmanov, A. Granier, T. Grünwald, K. Havránková, D. Janous, A. Knohl, T. Laurela, A. Lohila, D. Loustau, G. Matteucci, T. Meyers, F. Miglietta, J. M. Ourcival, D. Perrin, J. Pumpanen, S. Rambal, E. Rotenberg, M. Sanz, J. Tenhunen, G. Seufert, F. Vaccari, T. Vesala, and D. Yakir. 2005. On the separation of net ecosystem exchange into assimilation and ecosystem respiration: review and improved algorithm. Global Change Biology 11:1424–1439). Maximum values of the quantum yield (α=75 mmol · mol^?1), photosynthetic capacity (A_max=3.4 mg CO₂ · m^?2 · s^?1), gross photosynthesis (P_g,max=116 g CO₂ · m^?2 · d^?1), and ecological light-use efficiency (ε_ecol=59 mmol · mol^?1) of managed grasslands and high-production croplands exceeded those of most forest ecosystems, indicating the potential of nonforest ecosystems for uptake of atmospheric CO₂. Maximum values of gross primary production (8 600 g CO₂ · m^?2 · yr^?1), total ecosystem respiration (7 900 g CO₂ · m^?2 · yr^?1), and net CO₂ exchange (2 400 g CO₂ · m^?2 · yr^?1) were observed for intensively managed grasslands and high-yield crops, and are comparable to or higher than those for forest ecosystems, excluding some tropical forests. On average, 80% of the nonforest sites were apparent sinks for atmospheric CO₂, with mean net uptake of 700 g CO₂ · m^?2 · yr^?1 for intensive grasslands and 933 g CO₂ · m^?2 · d^?1 for croplands. However, part of these apparent sinks is accumulated in crops and forage, which are carbon pools that are harvested, transported, and decomposed off site. Therefore, although agricultural fields may be predominantly sinks for atmospheric CO₂, this does not imply that they are necessarily increasing their carbon stock.     

Assessment of an ECG event recorder in healthy dogs in a hospital environment

Ambulatory electrocardiography techniques are superior to standard electrocardiography in evaluating rhythm disturbances in dogs with episodic weakness or collapse. Disadvantages include cumbersome equipment, short recording periods and an inherent delay in trace analysis. A small programmable cardiac event recorder with combined automatic and owner-triggered recording capability was evaluated in 13 healthy dogs in a hospital environment. The unit was well tolerated and produced diagnostic recordings directly to a personal computer, with useful information about continuous heart rate. It detects premature complexes, pauses and bradycardias according to programmed detection thresholds. These events were counted frequently but trace review revealed concerns regarding specificity. Recordings were often triggered by sinus arrhythmia, sinus tachycardia and unclassifiable rate changes rather than by clinically significant arrhythmias. Correct detection of ventricular ectopic complexes, a single supraventricular premature complex, sinus arrest and second-degree atrioventricular block occurred in individual dogs. Visual review of all automatically recorded events was essential and significantly increased the time required for event recording analysis. Manual recordings might be more useful and the overall results suggest that further studies are warranted to evaluate the system in clinical cases in the home environment.